Stroboscope



M m 1929- i A. v. .1. GUILLET 1,705,446

STROBOSGOPE Filed March 1925 Patented Mar. 12, 1929.

UNITED STATES STROBOSCOPE.

Application filed March 7, 1925, Serial No. 13,775, and in France March 15, 1924.

The present invention relates to strobescopes in which the vibratory member consists of a vibrating string, the vibratory movement of which is sustained by electromagnetic means, for example by an electromagnct through which passes, at regular intervals of time, an electric current which is set up or cut out by the vibrating cord itself each time it passes through its position of equilibrium.

This invention has for its object to provide the vibrating cord with a contact member which, at each vibration of the cord, interrupts a circuit in which is inserted the primary winding of a transformer adapted to produce instantaneous periodic illuminating flashes or sparks, either by means of a condenser (for example a Leyden jar) for giving condensed sparks, or by means of a tube filled with rarefied gas, a neon tube of large surface for instance.

There may thus be obtained flashes or sparks of great intensity, enabling large spaces and even entire rooms to be strobescopically illuminated, which is of value when the movement of similar or conjugated parts has to be followed over a somewhat large extent. This method is particularly adapted for photographing in a given condition a moving piece or for microscopically examining small displacements. With a single stroboscope condensed sparks may be produced in different places, that is to say to some extent a stroboscopic distribution of light may be obtained.

Upon the annexed'drawing Fig. 1 represents diagrammatically by by way of example a form of construction of the device.

Fig. 2 is a partial corresponding view of a device adapted to impart to the string a vibration by torsion.

Fig. 3 is an end view corresponding to that of Fig. 2.

The device comprises a steel piano wire a, held at its ends in two grips 02 a one of which a is fixed to the frame 7), whilst the other a is movable so as to allow the tension of the wire to be adjusted at will. For this purpose, the grip a is extended by a screwthreaded rod (1. which is screwed in a nut a. which may be displaced by means of a milled head a turning in the frame it).

The vibratory movement of the cord is sustained by means of an electro-magnet c, which is supplied with current set up or cut out by the cord itself at. each ofits passages through its position of equilibrium; for this purpose, the cord (L carries, near its fixed end, a contact (I, opposite which is arranged a contact- 2, carried by micrometer screw (2 which allows the degree of contact between ($5 and e to be regulated.

In the middle of the cord wot .th'e stroboscope, which is stretched horizontally, a light rigid metal wire at is fixed, in the form of a bridge, having two arms of .unequal length m m Beneath the bridge is arranged a vessel n of insulating material, divided into two compartments n at, by a partition of glass or other insulating material. These compartments contain mercury to such a depth that the arm m constantly immersed in the mercury or the compartment n whilst the arm m emerges from the mercury of the compartment 11"" at each vibration of the cord. To the said compartments 12 n are connected the terminals of a circuit n in which is inserted the primary or of a transformer, the second ary winding a thereof being inserted in the circuit a, the terminals of which are connected to a neon tube a, of large surface. At each vibration of the cord a, the circuit n containing the primary n is broken, and a spark is given up by the neon tube a.

The frequency of the stroboscope may be varied by the wrapping of the cord, that is to say by winding around the cord a suitable wire, of copper or lead, for example as shown in a (Fig. 1).

Other frequencies may also be obtained by substituting for the tranverse vibration of the cord a vibration by tortion, for example by means of an arrangement such as is illustrated in elevation in Fig. 2 and in plan view in Fig. 3 of the accompanying drawings. A pallet 77, which is attracted by the actuating electro-magnet c at each passage of the current therethrough, is fixed at right angles to the cord 11 otithe stroboscope. A small blade. fixed to the end of the cord, is drawn by the torsion and makes or breaks the operating current. Adjustable masses 7;" enable the frequency of the vibrations by torsion to be varied.

it is to be understood that the. term vibration is intended to refer not only to iongitudinal vibrations but also to torsionai vi. brations of the cord.

hat I claim is:

1. A stroboscope, comprising avibra cord, means for securing the cord at its ends, electromagnetic means for sustaining vibration of the cord, a contact member carried by the cord, a circuit including the contactmember, a transformer inserted in the circuit and means. in circuit. with the transion mer for producing illuminating sparks.

2. A stroboscope, a comprising a vibratory cord, means for securing the cord at its ends, electromagnetic means for sustaining vibration of the cord, a contact member arried by the cord. a circuit cooperating with the contact member, a' transformer inserted in the circuit and a neon tube arranged to be supplied with current by the transformer.

3. A stroboscope, comprising a vibratory cord, means for securing the cord at its ends, electromagnetic means for sustaining vibration of the cord, a contact member in the form of a two armed bridge piece carried by the cord, two vessels insulated one from the other and containing mercury, arranged opposite the arms of the bridge piece so that one of the arms is constantly immersed in the mercury in one vessel and the other arm emerges from the mercury in the other vessel at each vibration of the cord, a circuit having its terminals respectively connected to the vessels, a transformer inserted in the circuit and means connected to the transformer for producing illuminating sparks.

4. A stroboscope, comprising a vibratory cord, means for securing the cord at its ends, electromagnetic means for sustaining vibration of the cord, a contact member carried by the cord, a circuit including the contact member, a transformer inserted in the circuit and means in circuit with the transformer for producing illuminating sparks. a wire wound around the vibratory cord for varying the frequency of the stroboscope.

In testimony whereof I have signed my name to this specification.

AMEDEE VICTOR JGSEPH GUILLET. 

